With the improvement of the society and the development of the economic, the general gasoline engine industry is provided with a good development platform. And the booming general gasoline engine industry further accelerates the development of its accessorial industries, one of which is the carburetor industry.
A carburetor is a equipment that mixes a certain amount of fuel and some air to keep the engine working normally, so as to prevent the engine from stopping work or damage under a “lacking fuel” condition, which is caused by that no sufficient fuel can be mixed with the air, and in turn, make the engine work more reliably and safely. Meanwhile, the carburetor monitors whether superfluous fuel is mixed with the air so as to insure the proportion of the mixed fuel and air and, in turn, prevent the engine from working under a “rich fuel” condition, which may cause the engine to stop working, generate a lot of smoke, and work in bad condition or waste fuel. Thus, the carburetor works as a head of an engine, and the performance of the carburetor plays an important role in the performance of the engine. Therefore, choosing a good carburetor is one of key factors to bring the engine into full play. However, the existing diaphragm carburetors have the following drawbacks:
As illustrated in FIG. 1 and FIG. 2, an existing diaphragm carburetor includes a carburetor body 21, a main adjutage 22, a throttle subassembly 23 and a choke subassembly 24. The carburetor body 21 is formed to be a main fuel supply channel which includes a gas inlet cavity 210a, a venturi 210b and a mixing cavity 210c. The main adjutage 22 is disposed on the venturi 210b. The throttle subassembly 23 includes a throttle spindle 231 pivoted to the carburetor body 21 and a throttle 232 mounted on the throttle spindle 231 for opening or closing the mixing cavity 210c. The choke subassembly 24 includes a choke spindle 241 pivoted to the carburetor body 21 and a choke 242 mounted on the choke spindle 241 for opening or closing the gas inlet cavity 210a. When starting, rotate the choke spindle 241 to make the choke 242 close the gas inlet cavity 210a, as the state shown in FIG. 1, at this time, the choke 242 prevents outer air from entering the venturi 210b, so as to cause the engine to start at a high density fuel state thereby increasing the probability of the successful start of the engine. After the engine starting, it is necessary to rotate the choke spindle 241 by manual means in a very short time to cause the choke 242 to fixedly connect with the choke spindle 241 thereby opening the gas inlet cavity 210a, as the state shown in FIG. 2, at this time, the outer air enters the venturi 210b in the direction of arrow shown in the gas inlet cavity 210a so as to meet the need of the engine for working normally.
However, aforementioned diaphragm carburetor needs to rotate the choke spindle 241 by manual means in a very short time to cause the choke 242 to open after the engine starting, otherwise the engine will flameout in a short time. On one hand, it is not convenient for the operation of the user, thereby increasing the burthen of the user. On the other hand, when the engine want to run for a long time to meet the need of warm-up, it needs to provide small hole formed in the choke 242 for more air entering, however, this will decrease the degree of vacuum at the main adjutage 22, the fuel ejected from the main adjutage 22 is not enough to mix with the air, thus the output mixed gas is so sparse that the engine can not start normally.